1. Field of the Invention
The present invention relates to a power conversion apparatus including semiconductor modules each incorporating a switching element and a circuit board on which a control circuit for controlling the semiconductor modules is formed.
2. Description of Related Art
Generally, a power conversion apparatus such as an inverter or a converter includes semiconductor modules and a circuit board on which a control circuit for controlling the semiconductor modules is formed. The circuit board on which various electronic components constituting the control circuit are mounted is connected with signal terminals of the semiconductor modules. The dimensions of the circuit board have to be sufficiently small for the power conversion apparatus to be compact in size. Japanese Patent Application Laid-open No. 2009-213307 describes a power conversion apparatus having the structure in which adjusting elements for adjusting the switching speeds of switching elements are mounted on both the front and back surfaces of a circuit board for the purpose of reducing the dimensions of the circuit board.
However, the above structure does not always make it possible to sufficiently reduce the dimensions of such a circuit board depending on the layout of the signal terminals.
In the power conversion apparatus described in the above patent document, each upper arm semiconductor module on the high potential side and the corresponding lower arm semiconductor module are aligned along the terminal arranging direction (the direction in which their signal terminals are arranged). Accordingly, to reduce the dimension in the terminal arranging direction of the circuit board, it is necessary to reduce the distance between the upper arm semiconductor module and the lower arm semiconductor modules as much as possible, and accordingly, it is necessary to reduce the distance between the upper arm terminal row (the row of the signal terminals of the upper arm semiconductor module) and the lower arm terminal row (the row of the terminals of the lower arm semiconductor module). However, in this case, it becomes difficult to provide a sufficient creepage distance between these rows.
In addition, since the space for forming connecting portions corresponding to the upper arm terminal row and the lower arm terminal row spreads out in the terminal arranging direction, the space for mounting other electronic components on the circuit board is restricted.